"It [the rivalry] is a positive and drives me on. The closer I get to him, or if I'm beating him, I know I'm up there in the world standard," he said.

You always want to run for Britain, but they can only choose one and unfortunately there is another Welsh guy called David Greene who is world champion, so it is just my luck isn't it?

Rhys WilliamsEuropean 400m Hurdle champion

Williams is among a number of senior athletes, including Paula Radcliffe, who have lost their National Lottery funding since London 2012, and he now works 20 hours a week for a company in Cardiff which supplies orthopaedic products.

"For the first time in my life, I have had to work," he said, describing his current lifestyle as "difficult and different".

"I am working part-time and I have been really lucky that somebody has taken me on. That has fitted in around training and helped me take my mind off training."

Williams is determined to challenge Greene's position, and is aware he has more work to do.

"To be fair, for it to be a rivalry, I have to start beating him. It is too one-sided at the moment and I need to do my bit."

Williams, a semi-finalist at the London Olympics, has made his best start to a track season and has already run the 'A' standard to qualify for the World Championships in Moscow this summer and the Commonwealth Games in Glasgow in 2014.

"Of course [I am disappointed]. You always want to run for Britain, but they can only choose one and unfortunately there is another Welsh guy called David Greene who is world champion, so it is just my luck isn't it?" said Williams.